This invention relates to a lean premix burner for the combustion chamber of a gas-turbine engine which has an annular central body which connects to a fuel line and employs a circumferential atomizer lip and a fuel-supplied film application surface provided thereon for the generation of an airflow-impinged fuel film.
Combustion chambers of gas-turbine engines can be provided with lean premix burners in order to enable a fuel-air mixture with high content of air to be burned in the combustion chamber at low combustion temperature and with correspondingly reduced formation of nitrogen oxide. In order to ensure ignition of the lean air-fuel mixture under any condition, for example also at low ambient temperatures and correspondingly adverse vaporization behavior, it is further known to combine the lean burner (main burner) with a supporting burner centrally integrated therein. On the burner of this type known from Specification EP 0 660 038 B1, swirler elements are arranged in the annular air feed channels for the supporting burner and the main burner to achieve strong air swirl and maximum mixture of the air with the fuel supplied downstream of the swirler elements. It has already been proposed to provide these swirler elements also in the form of aerodynamic air guide vanes to effect, at increased air mass flow, an even more intense mixture of fuel and air and uniform issue of the fuel-air mixture into the combustion chamber.
Furthermore, burners with an atomizer lip, also termed film applicator, are known, for example from Specification U.S. Pat. No. 6,560,964 B2. The annular atomizer lip, on which a continuous fuel film impinged by a concentric air flow is to be generated, significantly improves the atomization effect and the mixing of fuel and air. However, combustion and pressure oscillations may occur on lean premix burners with film applicators which are disadvantageous for the combustion process in the combustion chamber. To remedy this disadvantage, expensive passive dampers (Helmholtz resonators) are, for example, employed in the combustion chamber.